Chronic Diarrhea

Diarrhea Loosely defined as passage of abnormally liquid or unformed stools at an increased frequency. Adults (typical western diet)  stool weight > 200g/d caused by an imbalance in the physiologic mechanisms of the GI tract, resulting in impaired absorption and/or excessive secretion.

2 common conditions (<200 g/d) must be distinguished from diarrhea: ◦ Pseudodiarrhea  Frequent passage of small volumes of stool  Associated with rectal urgency ; accompanies IBS/proctitis ◦ Fecal Incontinence  involuntary discharge of rectal contents  most often caused by neuromuscular disorder/structural/anorectal problems

Diarrhea TypeDuration Acute < 2 weeks Persistent2-4 weeks Chronic> 4 weeks

Chronic Diarrhea Warrants evaluation to exclude serious underlying pathology Most of the causes: NON- infectious Classification by pathophysiological mechanism  rational approach to management

Approach to Chronic Diarrhea: Laboratory tools are extensive  costly and invasive  rationally directed by a careful History and PE. When this strategy is unrevealing, simple triage tests (Hx, PE, routine blood studies) are often warranted. ◦ Characterize the mechanism of diarrhea ◦ Identify diagnostically helpful assoc. ◦ Assess px’s fluid/electrolyte & nutritional status

HISTORY Family History: IBD Sprue Presence of : fecal incontinence fever weight loss pain exposure(travel, medications, contacts) common extraintestinal manifestations (skin, arthralgias, oral aphtous ulcers Diarrhea Onset Duration Pattern Aggravating and relieving factors (diet) Characteristics

Physical Findings Thyroid mass Wheezing Murmurs Edema Hepatomegaly Abdominal masses Lymphadenopathy Mucocutaneous abnormalities Perianal fistula Anal sphincter laxity Celiac disease Blood Studies Peripheral blood leukocytosis ↑ sedimentation rate C- reactive protein Anemia Eosinophilia Tissue transglutaminase Ab Inflammation Blood loss/nutritional deficiency Parasites, neoplasia, collagen vascular disease, allergy, eosinophilic gastroenteritis Celiac disease

Chronic Diarrhea 2/3 of cases, the causes remain unclear after the initial encounter  further testing is required: ◦ Quantitative stool collection and analyses  important objective data and establish a diagnosis/characterize the type of diarrhea as a triage for focused additional studies ◦ Stool ( >200g/d )  electrolyte concentration, pH, occult blood testing, leukocyte inspection/protein assay, fat quantitation, and laxative screens.

Chronic Diarrhea When a specific diagnosis is suggested on the initial encounter, therapeutic trial is often appropriate, definitive, and highly cost effective. Examples: ◦ Chronic watery diarrhea  ceases with fasting in an otherwise healthy young adult  may justify a trial of lactose-restricted diet ◦ Bloating w/ diarrhea after a mountain backpacking trip  trial of metronidazole (giardiasis) Any patient with chronic diarrhea + hematochezia  evaluated with stool microbiologic studies and colonoscopy

Chronic Diarrhea Secretory diarrheas ◦ Microbiologic studies should be done, including: fecal bacterial cultures, inspection for ova and parasites and Giardia antigen assay ◦ Suggested history & other findings  screening for peptide hormones (gastrin, VIP, calcitonin, TH/TSH, urinary 5-HIAA, and histamine) ◦ Upper endoscopy, colonoscopy w/ biopsy and small bowel barium x-rays  rule out structural/occult inflammatory disease

Chronic Diarrhea Osmotic diarrhea ◦ Tests for 2 most common causes:  Lactose intolerance/malabsorption  lactose breath testing or therapeutic trial w/ lactose exclusion & lactose challenge  Magnesium ingestion  fecal magnesium levels ◦ pH  low fecal pH suggests CHO malabsorption Steatorrhea ◦ Endoscopy w/ small bowel biopsy(includes aspiration for Giardia and quantitative cultures) ◦ Small-bowel radiograph ◦ (-) radiograph/ pancreatic exocrine disease  Pancreatic exocrine insufficiency ruled out  secretin- cholecystokinin stimulation test

Chronic Diarrhea Chronic inflammatory-type of diarrheas (presence of blood/leukocytes in the stool) ◦ Stool cultures ◦ Inspection for ova/parasites ◦ C. difficile toxin in assay ◦ Colonoscopy w/ biopsies ◦ Small-bowel contrast studies